Better service doesn't actually beget better tips
Diners love the power to bestow or withhold financial reward at their whim; servers, in turn, seem to be motivated by the idea that really excellent service could be rewarded by a monster gratuity. The trouble is, that's not actually how things pan out in practice. Michael Lynn, a professor at Cornell's School of Hotel Administration, has spent his career researching tipping behaviors, and found that perceived service quality only accounts for two percent of the variation between tips. Two percent! It's probably not even enough to be picked up on by the server, much less cause a significant change in behaviour.
http://www.esquire.com/food-drink/re...egal-15603180/